A Brief History of Cryptography: Sending Secret Messages Over Time

From the Greek word meaning ‘hidden writing’ encryption The science of obfuscating transmitted information so that it can only be interpreted by the intended recipient. Since ancient times, the practice of sending secret messages has been common in almost all major civilizations. In modern times, encryption has become an important core. cyber security. From securing everyday personal messages and authenticating digital signatures to protecting online shopping payment information and even protecting top secret government data and communications, encryption makes digital privacy possible.

Although the history of these practices dates back thousands of years, the use of cryptography and the broader field of cryptography are still considered relatively young, having made tremendous progress over the past 100 years. The beginning of the digital age, coinciding with the invention of modern computing in the 19th century, heralded the birth of modern cryptography. As an important means of building digital trust, mathematicians, computer scientists, and cryptography experts have begun developing modern encryption techniques and encryption systems to protect sensitive user data from hackers, cybercriminals, and prying eyes.

Most cryptographic systems start with an unencrypted message known as plaintext. encrypted It uses one or more encryption keys to transform it into an indecipherable code called ciphertext. This ciphertext is then sent to the recipient. If the ciphertext is intercepted and the encryption algorithm is strong, the ciphertext is useless to an unauthorized eavesdropper because the code cannot be decrypted. However, the intended recipient can easily decrypt the text, assuming they have the correct decryption key.

In this article, we will look back on the history and evolution of encryption.

ancient cryptography

1900 BC: One of the first implementations of cryptography was found in the use of non-standard hieroglyphs carved into the walls of tombs in the Old Kingdom of Egypt.

1500 BC: Clay tablets discovered in Mesopotamia contained coded writing believed to be the secret to ceramic glazes, which in today’s terms might be considered a trade secret.

650 BC: The ancient Spartans used early transposition ciphers to scramble the order of letters in military communications. The process involves writing a message on a piece of leather wrapped around a hexagonal wooden staff known as a scytale. Once the strips are wound into the correct size sickletail, the letters line up to form a coherent message. However, when the strip is unraveled, the message is reduced to ciphertext. In the Skytail system, a certain size of Skytail can be considered a private key.

100-44 BC: To share secure communications within the Roman army, Julius Caesar is known to have used an alternative cipher called the Caesar Cipher. A substitution cipher replaces each character in plaintext with another character determined by moving a set number of characters forward. Or backwards within the Latin alphabet. Therefore Symmetric key cryptosystemThe specific steps and direction of character transposition are the private keys.

medieval cryptography

800: The Arab mathematician Al-Kindi invented the technique of frequency analysis for cryptography, one of the most monumental innovations in cryptography. Frequency analysis uses linguistic data, such as the frequency of specific letters or letter pairs, parts of speech, and sentence composition, to reverse engineer your personal decryption key. Frequency analysis techniques allow code breakers to quickly perform brute force attacks where they attempt to systematically decrypt an encoded message by systematically applying potential keys to eventually find the correct key. Single-alphabetic substitution ciphers that use only one alphabet are vulnerable to frequency analysis, especially if the private key is short and weak. Al-Kandi’s writings also covered cryptanalysis techniques for multi-alphabetic ciphers, turning plaintext into ciphertext of multiple alphabets to add a layer of security that is much less vulnerable to frequency analysis.

1467: The work of Leon Battista Alberti, considered the father of modern cryptography, most clearly explored the use of ciphers incorporating multiple alphabets, known as the polyphonic cipher system, the most powerful form of encryption of the Middle Ages.

1500: Although actually published by Giovan Battista Bellaso, the Vigenère cipher has been misattributed to the French cryptographer Blaise de Vigenère and is considered a landmark polyphonic cipher of the 16th century. Vigenère did not invent the Vigenère Cipher, but in 1586 he created a stronger automatic key cipher.

modern encryption

1913: With the outbreak of World War I in the early 20th century, cryptography for military communications and cryptography for code-breaking increased rapidly. The success of British cryptographers in deciphering the German telegraph code led to a decisive victory for the Royal Navy.

1917: American Edward Heber combined electrical circuits and mechanical typewriter parts to create the first crypto-rotor machine, which automatically scrambled messages. A user can type a plain text message on a standard typewriter keyboard, and the machine automatically generates a replacement password, outputting a passphrase by replacing each letter with a random new character. The ciphertext can be decoded by manually flipping the circuit rotor and then feeding the ciphertext back into the Hebern Rotor Machine to produce the original plaintext message.

1918: In the aftermath of the war, German cryptographer Arthur Scherbius developed the Enigma Machine, an advanced version of Hebern’s rotor machine. The machine also used rotor circuits to encode plaintext and decode ciphertext. The Enigma Machine, heavily used by the German military before and during World War II, was considered suitable for the highest level of top-secret encryption. However, like Hebern’s Rotor Machine, decrypting messages encrypted with the Enigma Machine required machine calibration settings and advanced sharing of private keys, making it vulnerable to espionage and ultimately leading to Enigma’s downfall.

1939-45: With the outbreak of World War II, Polish code breakers left Poland and joined many prominent and famous British mathematicians, including Alan Turing, the father of modern computing, to work on the German Enigma cipher system, which was an important breakthrough for the Allies. has been deciphered. Turing’s work established much of the fundamental theory of algorithmic computation, among other things.

1975: Researchers working on block ciphers at IBM developed the Data Encryption Standard (DES), the first encryption system certified by the National Institute of Standards and Technology (then known as the American Bureau of Standards) for use by the U.S. government. DES was powerful enough to thwart even the most powerful computers in the 1970s, but its short key length makes it insecure for modern applications. However, DES’s architecture had and continues to have a significant impact on the evolution of cryptography.

1976: Researchers Whitfield Hellman and Martin Diffie introduced the Diffie-Hellman key exchange method for securely sharing encryption keys. This makes new forms of encryption possible. asymmetric key algorithm. These types of algorithms, also known as public key cryptography, provide a much higher level of privacy by no longer relying on a shared private key. In a public key cryptosystem, each user has his or her own private secret key that works in conjunction with the shared public key for additional security.

1977: Ron Rivest, Adi Shamir, and Leonard Adleman introduce the RSA public key cryptosystem, one of the oldest encryption technologies for secure data transmission still in use today. RSA public keys are generated by multiplying large prime numbers. This is incredibly difficult for even the most powerful computers to factor without prior knowledge of the private key used to generate the public key.

2001: With advances in computing power, DES has been replaced by the more powerful Advanced Encryption Standard (AES) encryption algorithm. Like DES, AES is a symmetric encryption system, but it uses much longer encryption keys that cannot be decrypted by modern hardware.

Quantum cryptography, post-quantum cryptography and the future of cryptography

The field of cryptography continues to evolve to keep pace with technological advancements and become increasingly sophisticated. cyber attack. quantum cryptography (also known as quantum cryptography) refers to the applied science of securely encrypting and transmitting data based on naturally occurring and immutable laws of quantum mechanics for use in cybersecurity. Although still in its infancy, quantum cryptography has the potential to be much more secure than previous types of encryption algorithms and, in theory, may even be impossible to hack.

Not to be confused with quantum cryptography, which relies on the natural laws of physics to create a secure cryptographic system, post-quantum cryptography (PQC) algorithms use different types of mathematical cryptography to create quantum computer-proof cryptography.

According to the National Institute of Standards and Technology (NIST): (link external to ibm.com), The goal of post-quantum cryptography (also known as quantum-resistant or quantum-safe) is “to develop cryptographic systems that are secure for both quantum and classical computers and interoperable with existing communication protocols .” And the network.”

Learn how IBM encryption solutions help businesses protect their sensitive data.

IBM Cryptography Solutions combine technology, consulting, systems integration and managed security services to ensure cryptographic agility, quantum safety, robust governance and risk compliance. From symmetric encryption to asymmetric encryption, hash functions, and more, ensure data and mainframe security with end-to-end encryption tailored to your business needs.

Explore IBM encryption solutions